Method of producing of cellulose ester film

ABSTRACT

In order to produce a cellulose ester film constructed of a front layer, an intermittent layer and a rear layer, a dope solution is doped on a supporter. In at least one of the front layer and the rear layer, a mass ratio of a cotton linter to a wood pulp (cotton linter/wood pulp) is between 5/95 and 0/100, and a solvent of the dope contains more than 15 wt. % alcohols and hydrocarbons whose carbon number each is 1-10. Further, a ratio of a solid content density of a solution for forming the front layer and the rear layer to a solid density of a solution for forming the intermittent layer is less than 0.9 wt. %, and a total thickness of the solutions for front and rear layers is more than 5% of the dope ribbon.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method of producing of acellulose ester film which is used for a deflector protect film and anoptical compensation film.

[0003] 2. Description Related to the Prior Art

[0004] A deflector protect film and an optical compensation film areproduced of a cellulose ester film, such as cellulose triacetate film(hereinafter TAC film) and the like. The TAC film is produced in amethod for producing a film from a solution. In the method additives aresolved in a solvent to produce a high molecular solution (dopesolution), and thereafter the dope solution is doped on a supporter witha die having a slit, dried for a predetermined time, peeled from thesupporter, and further dried again to produce the TAC film.

[0005] When the dope solution is dried for a long time thereby, thesolvent in the dope solution is evaporated to form a skinning of highmolecular material on both edges of the slit of the die. The skinningprevents the doping of the dope solution, and causes the thickness inboth edges of the dope solution on the supporter to become uneven.Further sometimes the skinning falls down from the both edges of theslit of the die. In this case, the skinning adheres on a feed roller todamage the TAC film dried from the dope solution on the supporter. Inorder to prevent the generation of the skinning, U.S. Pat. No.3,112,528, Japanese Patent Laid-Open Publications No. 2-208650 and5-86212 describe methods in which the solvent is flown to solve solutesin the dope solution or a mixture of the evaporated solvent and air areblown.

[0006] However, in the above methods, the amount of the mixture and thesolvent is hardly regulated. Accordingly vibration of edges of a doperibbon between the die and the supporter causes to generate theskinning.

[0007] Further, the deflector protect film is applied to one of bothside of a deflector. The deflector is formed of a polyvinylalcohol film(hereinafter PVA film). The PVA film is extended on a shaft for dieingin iodine or to color dyne, and otherwise after dying the PVA film isextended, and bridges with boron compound to produce the deflector.

[0008] Several types of the cellulose ester films are proposed. Forexample, Japanese Patent Laid-Open Publication No.6-134933 proposes acellulose triacetate laminate film having a cellulose triacetate filmproduced from cotton and pulp for easy peeling and improving the heatresistance. Further, Japanese Patent Laid-Open Publication No.2000-19776 proposes a cellulose ester film whose averaged substitutiondegree is 2.88-3.00 to always prevent the generation of optical creases.

SUMMARY OF THE INVENTION

[0009] An object of the present invention is to provide a method ofproducing a cellulose ester film, in which the generation of a skinningis prevented.

[0010] Another object of the present invention is to provide a method ofproducing a cellulose ester film used for a deflector protect film andan optical compensation film.

[0011] Still another object of the present invention is to provide amethod of producing the cellulose ester film used for deflector plate,in which optical non-uniformity does not occur in edges of a corner of aliquid crystal indicator with a deflector to which a deflector protectfilm is applied

[0012] In order to achieve the objects and other objects, in a method ofthe present invention for forming the cellulose ester film having front,intermittent and rear layers, the dope solution to be doped on asupporter is composed of a first solution for forming the front layer, asecond solution for forming the intermittent layer and the thirdsolution for forming the rear layer. A ratio A/B of a sharing viscosityA of the first or third solution to a sharing viscosity B of the secondsolution is under 0.9.

[0013] Further, in a second embodiment of the method of the presentinvention, the cellulose ester film is produced by using a die havingplural manifolds, and each manifold contains a solutions. The dopesolution is composed of the solutions and doped on a supporter. Thesolvent of the dope solution is alcohol having 1-10 carbons and included15 wt. % hydrocarbon. The dope solution is dried on the supporter toform the cellulose ester film, and then the cellulose ester film ispeeled from the supporter. Thereafter, the cellulose ester film is driedsuch that in at least one of surface layers of the plural layers a ratioof cotton linter and wood pulp is between 5 to 95 and 0 to 100.

[0014] By doping the dope solution, a total thickness of the solutionsfor the surface layers is more than 5% of the thickness of a doperibbon. Furthermore, to the dope solution is fed a mixed solventcontaining a bad solvent between 30-90% to a solute of the dopesolution.

[0015] In the third embodiment of the method of the present invention,the die provided with a feed block is used for doping the dope solutionto form the cellulose ester film having plural layers. In the forthmethod of the present invention, plural dies are used for doping thedope solutions so as to form a same number of layer in the celluloseester film as the dies.

[0016] According to the present invention, it is prevented to generatean optical skinning in a corner of a liquid crystal indication deviceand creases on an end of a slit. Further, the quality of the celluloseester film becomes higher.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above objects and advantages of the present invention willbecome easily understood by one of ordinary skills in the art when thefollowing detailed description would be read in connection with theaccompanying drawings:

[0018]FIG. 1 is a schematic diagram of a device for producing acellulose ester film;

[0019]FIG. 2A is a sectional view of the cellulose ester film;

[0020]FIG. 2B is a sectional view of the cellulose ester film;

[0021]FIG. 3A is a sectional view of the cellulose ester film having asurface layer;

[0022]FIG. 3B is a sectional view of the cellulose ester film having twosurface layers;

[0023]FIG. 4 is a side view of a die and a feed block;

[0024]FIG. 5A is a sectional view of a part of the die in a situation ofdoping a dope solution;

[0025]FIG. 5B is a schematic sectional view of the feed block;

[0026]FIG. 6A is a sectional view of a dope ribbon;

[0027]FIG. 6B is an exploded sectional view of an edge of the doperibbon;

[0028]FIG. 7 is an exploded sectional view of a die having threemanifolds;

[0029]FIG. 8 is an exploded sectional view of three dies;

[0030]FIG. 9 is a schematic view of a doping section and a dryingsection of the second embodiment;

[0031]FIG. 10 is a schematic view of a doping section and a dryingsection of the third embodiment;

[0032]FIG. 11 is a schematic view of a doping section and a dryingsection of the forth embodiment;

[0033]FIG. 12 is a schematic view of a doping section and a dryingsection of the fifth embodiment;

[0034]FIG. 13 is a schematic view of a doping section and a dryingsection of the sixth embodiment;

[0035]FIG. 14 is a schematic view of a doping section and a dryingsection of the seventh embodiment;

[0036]FIG. 15 is a schematic view of a doping section and a dryingsection of the eighth embodiment;

[0037]FIG. 16 is a schematic view of a doping section and a dryingsection of the ninth embodiment;

[0038]FIG. 17 is a schematic view of a doping section and a dryingsection of the tenth embodiment.

PREFERRED EMBODIMENTS OF THE INVENTION Polymer

[0039] As high molecular material (polymer) used for a dope solution ofthe present invention, there are polyamides, polyolefines (for examplenorbornene polymers and the like), polystyrenes, polycarbonates,polysulfates, polyacrylates, polymehtacrylic acids (for examplepolymethylmethacrylate and the like), polyetheretherketones, polyvynilalcohols, polyvynil acetates, cellulose derivatives (low fatty acidesters of cellulose and the like). The low fatty acid esters ofcellulose (cellulose acylate) are especially preferable.

[0040] A low fatty acid of the low fatty acid ester of cellulose hasless than 6 carbons. The preferable number of the carbon is 2 (celluloseacetate), 3 (cellulose propionate) or 4 (cellulose butylate). Thecellulose acetate is much preferable and the cellulose triacetate(Acetification degree: 58.0-62.5%) is especially preferable. Further amixture of fatty acid esters may be used, for example, cellulose acetatepropionate and cellulose acetate butylate.

Solvent

[0041] According to solvent, organic solvent is preferable to inorganicone. As the organic solvent, there are hydrocarbon chloride (methylenechloride), ketones (for example acetone, methylethylketone,cycrohexanone and the like), esters (methylfolmate, methyl acetate,ethyl acetate, amyl acetate, butyl acetate and the like), ethers (forexample dioxane, dioxorane, tetrahydrofrane, dyethyl ether,methyl-t-butyl ether and the like), aromatic hydrocarbon (for examplebenzene, toluene, xylene and the like), fatty hydrocarbons (for examplehexane and the like), and alcohols (for example methanol, ethanol,n-propyl alcohol, isopropyl alcohol, n-butanol and the like).

[0042] The solvent is preferably swollen. Accordingly, the sort of thesolvents is determined in accordance with polymers which are used. Forexample, when as the polymer cellulose triacetate, polycarbonates andpolyesters are used, acetone or acetylic acid methyl is used as apreferable solvent. Further, benzene, toluene, xylene, hexane, acetone,methylethylketone are preferably used for norbornen polymers.Furthermore, acetone, methylethylketone, methylacetate, butylacetate ormethanol are used for polymethylmethacrylate. Note that more than twokinds of solvents may be mixed and used.

[0043] Considering to harmful influences on human bodies andcircumstances, materials containing chlorine, such as methylenechloride,may not be used. For producing the dope solution, ketones and alcoholsmay be mixed. Especially when cellulose acylate is used as polymer,methyl acetylate is preferably used as it easily solves. Further,acetylic acid methyl may more easily solve in mixture of ketones andalcohols. In this case, according to a ratio of each solvent, acetylicacid methyl is 20-90 wt. %, ketones are 50-60 wt. %, and alcohols are5-30 wt. %.

[0044] A boiling point of solvent composing the dope solution ispreferably 20-300° C., particulally 30-200° C., especially 40-100° C.

Additives

[0045] Plasticizer, ultraviolet absorptive material, deteriorationinhibitor may be added as the additives to the dope solution.

Plasticizer

[0046] As the plasticizer used in the present invention, there arephosphoric acid ester plasticizer (for example triphenylphosphate,tricresylphosphate, cresyldiphenyl phosphate, octyldiphenylphosphate,diphenylbiphenyl phosphate, trioctylphosphate, tributylphosphate and thelike), phthalic acid ester plasticizer (for example diethylphthalate,dimethoxyethylphthalate, dimethylphthate, dioctylphthalate and thelike), grycolic acid ester plasticizer (for example triacetine,tributyline, butylphthalylbutylbricolate, ethylphthalylethylgricolate,methylphthalylethylgricolate, butylphthalylbutylgricolate and the like).Some of the plasticizer may be mixed. Further, other plasticizersdescribed in Japanese Patent Laid-Open Publication No. 11-80381,11-124445, 11-248940 may be also used. The plasticizers are preferablycontained 0.1-20 wt. % to the polymer in the dope solution, particularly6-16 wt. %.

Ultraviolet Absorptive Material

[0047] Ultraviolet absorptive materials may be added in the dopesolution. Especially the dope solution may contain one or more sorts ofultraviolet absorptive materials. A film produced in a method of thepresent invention is often used as an optical material for liquidcrystal monitor. In this case, the ultraviolet absorptive materialshould effectively absorb ultraviolet ray under 370 nm of wave length inview of preventing deterioration of the liquid crystal, and hardlyabsorb visible ray above 400 nm of wave length in view of indicationprobability of the liquid crystal. For example, there areoxybenzophenone compounds, benzotriazol compounds, salycilic acid estercompounds, bensophenone compounds, cyanoacrilate compounds, nickelcomplex salt compound, and the like. Particularly preferable arebenzotriazol compounds and benzophenone compounds. Especiallybenzophenone compound hardly makes a unnecessary coloring of thecellulose ester. The benzotriazol ultraviolet compounds include thosedescribed in Japanese Patent Laid-Open Publication 8-29619. Further,ultraviolet absorptive materials already known, such as described inJapanese Patent Laid-Open Publication No. 8-23950, may be also used. Theultraviolet absorptive material is preferably contained in 0.001-5 wt.%.

[0048] As the preferable ultraviolet absorptive material, there are, forexample, 2,6-di-tert-butyl-p-crezol,pentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethylenegrycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-3,5-di-tert-butyl-4-hydroxyphenyl propionate],2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylanilino)1,3,5-triazine, 2,2-thio-diethylene-bis[3-(3,5-di-tert-butyl-4-hydrozypheny)propionate,Octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,N,N′-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-hydrocynenamide),1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydrozybenzil)benzene,tris-(3,5-di-tert-butyl-4-hydroxybenzil) -isocianulate.

[0049] Especially preferable are 2,6-di-tert-butyl-p-crezol,pentaerythrytyl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate],triethyleneglycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate]. Metal deactivators of hydradine compounds, for example,N,N′-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionyl]hydradine, andphosphate processing stabilizer, such astris(2,4-di-tert-butylphenyl)phosphite may be mixed and used. Suchcompounds are preferably contained in 0.001-5 wt. % to the polymer inthe dope solution.

Particle Powders

[0050] The dope solution preferably contains mat materials of particlepowders for improving an adhering endurance property under high moistureof the film. A height of protrusions on a surface of the mat material ispreferably 0.005-10 μm, particularly 0.01-5 μm. The number of theprotrusions is preferably large. However, when it is larger thannecessary, the protrusions cause to generate haze. The mat materials maybe inorganic and organic and may be sometimes formed in ball-shape inspray-dry method or diffusing method. As inorganic mat materials, thereare barium sulfate, manganese colloid, titanium dioxide, bariumstrontium sulfate, silicon dioxide, aluminum oxide, zinc oxide, tinoxide, calcium carbonate, talc, caoline, calcium sulfate. Further, thereare silicone dioxide, (for example synthetic silica obtained by gelatingsilicic acid of in wet processing) and titanium dioxide produced fromtitanslag and sulfuric acid. The inorganic mat material may be obtainedalso by milling inorganic compound whose diameter is more than 20 mm.Thereafter, the classification of inorganic compound is carried out forexample by (vibrating filtration, wind power classification).

[0051] As the organic compound, there are polytetrafluoroethylene,cellulose acetate, polystyrene, polymethylmethacrilate,polypropylmethacrilate, polymethyl acrilate, polyethylene carbonate,acrylstyrene resins, silicone resins, polycarbonate resins,benzoguanamine resins, melanine resins, polyolefin resins, polyamideresins, polyimide resins, polyfluoroethylene resins and starch. Thereare further high molecular compound synthesized in suspensionpolymerization. However, when the amount of the particle powders is toolarge in the dope solution, the resiliency of the film becomes lower.Accordingly, the dope solution preferably contain the particle powdersin 0.001-5 wt. % to the polymer.

Fluoride Surface-active Agent

[0052] In the dope solution, fluoride surface-active agents may be alsoadded. The fluoride surface-active agents have a hydrophobic group offluorocarbon chain, and is used as coating agent in organic solvent or aantistatic agent while it decreases a surface tension. As the fluoridesurface-active agent there are, for example, C₈F₁₇CH₂CH₂O—(CH₂CH₂O)₁₀—OSO₃Na,

[0053] C₈F₁₇SO₂N(C₃H₇) (CH₂CH₂O)₁₆—H,

[0054] C₈H₁₇SO₂N(C₃H₇)CH₂COOK, C₇F₁₅COONH₄,

[0055] C₈H₁₇SO₂N(C₃H₇)CH₂CH₂O)₄—(CH₂)₄—SO₃Na,

[0056] C₈H₁₇SO₂N(C₃H₇) (CH₂)3-N⁺(CH₃)₃I⁻,

[0057] C₈F₁₇SO₂N(C₃H₇)CH₂CH₂CH₂N⁺(CH₃)₂—CH₂COO⁻, C₈F₁₇CH₂CH₂O(CH₂CH₂O)₁₆H,

[0058] C₈F₁₇CH₂CH₂O(CH₂)₃—N⁺(CH₃)₃I³¹,

[0059] H (CF₂)₈—CH₂CH₂OCOCH₂CH (SO₃) COOCH₂CH₂CH₂—(CF₂)₈—H

[0060] H (CF₂)₆CH₂CH₂O(CH₂CH₂O)₁₆—H,

[0061] H (CF₂)₈CH₂CH₂OCOCH₂CH (SO₃) COOCH₂CH₂CH₂CH₂C₈F₁₇,

[0062] C₉F₁₇—C₆H₄—SO₂N(C₃H₇) (CH₂CH₂O)₁₆—H,

[0063] C₉F₁₇—C₆H₄—CSO₂N(C₃H₇) (CH₂)C—N⁺(CH³)³I ⁻.

[0064] The amount of the fluoride surface active agent in the dopesolution is preferably 0.001-2 wt. % to the polymer.

[0065] Further, in the dope solution, several sorts of the additives maybe added to the solution. As the additives there are thermostabilizer,antistatic agent, flame retardant, lubricant, oils and the like that arefor example salt of alkali earth metal such as calcium and magnesium.

Mold Releasing Agent

[0066] In the dope solution, a mold releasing agent may be added. Thedope solution is doped on a supporter and dried thereon to the film. Byadding the mold releasing agent, the film may be easily peeled from thesupporter. As the mold releasing agent, there are waxes having highmelting point, high fatty acid, salts and esters thereof, silicone oil,polyvinyl alcohol, low molecular polyethylene, plant protein derivativesand the like. The amount of the molding releasing agent is preferably0.002-2 wt. % to the polymer in the dope solution not so as to harmfullyinfluence on luster and smoothness of the surface of the film.

Mold Releasing Accelerator

[0067] In the dope solution, a mold releasing accelerator may be added.As the mold releasing accelerator, surface-active agents are especiallypreferable, and described in Japanese Patent Laid-Open Publication No.61-243837. There are phosphorus type, carbon type, nonionic type,cationic type and the like in the surface active agent. The amount ofthe molding releasing accelerator is0.002-2 wt. %,preferably 0.005-1 wt.%, especially 0.01-0.5 wt. %.

[0068] The mold releasing accelerators are described as follows:

(R₁—B₁—O)_(n1)—P (═O)—(OM₁)_(n2)  Formula (1)

R₂—B₂—X  Formula (2)

[0069] Herein R₁ and R₂ are alkyl group, alkenyl group, alarkyl groupand aryl group; M₁ is alkali earth metal, ammonia, lower alkylamine.B1and B2 are coupling group of two valencies; X is carbonic acid (orsalt thereof), sulfenic acid (or salt thereof) and sulfuric acid ester(or salt thereof). n1 is the number of “1” or “2”, and n2 is integer of(3−n1).

[0070] Preferable examples of R₁ and R₂ are non-substituted alkyl groupwhich has 4-40 carbons (butyl, hexyl, octyl, 2-ethylhexyl, nonyl,dodecyl, hexadecyl, octadecyl, eicosanyl, docosanyl, myricyl and thelike), non-substituted alkenyl group which has 4-40 carbons (2-hexenyl,9-decenyl, oleyl and the like), substituted and non-substituted arylgroup which has 4-40 carbons (phenyl, naphtyl, methylphenyl,dimethylphenyl, trimethylphenyl, ethylphenyl, propylphenyl,di-isopropylphenyl, tri-isopropylphenyl, t-butylphenyl,di-t-butylphenyl, tri-t-butylphenyl, isopentylphenyl, ectylphenyl,isooctylphenyl, isononylphenyl, diisononylphenyl, dodecylphenyl,isopentadecylphenyl and the like).

[0071] Especially preferable are hexyl, octyl, 2-ethylhexyl, nonyl,dodecyl, hexadecyl, octadecyl, docosanyl, alkenyl, phenyl, naphtyl,tri-methylphenyl, di-isopropylphenyl, tri-isopropylphenyl,di-t-butylphenyl, tri-t-butylphenyl, isooctylphenyl, isononylphenyl,di-isononylphenyl and dodecylisonetadecylphenyl.

[0072] B₁ and B₂ are alkylene having 1-10 carbons, polyoxiethylene(degree of polymerization: 1-50), polyoxipropylene (degree ofpolymerization: 1-50), polyoxiglycerin and a mixture thereof. Preferableexamples of B₁ and B₂ are methylene, ethylene, propylene, butylenes,polyoxiethylene (degree of polymerization: 1-25), polyoxipropylen(degree of polymerization: 1-25), polyoxiglicerin (degree ofpolymerization: 1-15). Preferable examples of X are sulfonic acid,sulfuric acid ester, and their salt with Na, K, ammonium, trimethylamineand triethanolamine.

[0073] The preferable embodiments of the mold releasing accelerators arerepresented in the following formulars:

[0074] RZ-1: C₈H₁₇O—P(═O)—(OH)₂

[0075] RZ-2: C₁₂H₂₅O—P(═O)—(OK)₂

[0076] RZ-3: C₁₂H₂₅OCH₂CH₂O—P(═O)—(OK)₂

[0077] RZ-4: C₁₅H₃₁(OCH₂CH₂)₅O—P(═O)—(OK)₂

[0078] RZ-5: {C₁₂H₂₅O(CH₂CH₂O)₅}₂—P(═O)—OH

[0079] RZ-6: {C₁₈H₃₅(OCH₂CH₂)₈O }₂—P(═O)ONH₄

[0080] RZ-7: (t-C₄H₉)₃-C₆H₂—OCH₂CH₂O—P(═O)—(OK)₂

[0081] RZ-8: (iso-C₉H₁₉—C₆H₄—O—(CH₂CH₂O)₅—P(═O)—(OK)OH

[0082] RZ-9: C₁₂H₂₅SO₃Na

[0083] RZ-10: C₁₂H₂₅OSO₃Na

[0084] RZ-11: C₁₇H₃₃COOH

[0085] RZ-12: C₁₇H₃₃COOHN(CH₂CH₂OH)₃

[0086] RZ-13: iso-C₈H₁₇—C₆H₄—O—(CH₂CH₂O)₃—(CH₂)₂SO₃Na

[0087] RZ-14: (iso-C₉H₁₉)₂C₆H₃—O—(CH₂CH₂O)₃—(CH₂)₄SO₃Na

[0088] RZ-15:sodium triisopropylnaphthalenesulfonate

[0089] RZ-16:sodium tri-t-butylnaphthalenesulfonate

[0090] RZ-17: C₁₇H₃₃CON(CH3) CH₂CH₂SO₃Na

[0091] RZ-18:C₁₂H₂₅—C₆H₄SO₃.NH₄

[0092] Further, Japanese Patent Laid-Open Publication No. 10-316701describes acids and salts thereof as the preferable examples of the moldreleasing accelerator. Acid dissociaion constant pKa of the acids andsalts is 1.93-4.50, preferably 2.0-4.4, particularly 2.2-4.3 andespecially 2.6-4.3.

[0093] The acid may be organic or inorganic acid. As the inorganic acid,there are, for example, HClO₂ (2.31), HOCH (3.48), Molybdic acid (H₂,MoO₄: 3.62), HNO₂, (3.15), phosphoric acid (H₃, PO₄: 2.15),tri-polyphosphoric acid (H₅, P₃, O₁₀: 2.0), vanadic acid (H₃, VO₄: 3.78)and the like. As the organic acid, there are fat group monocarbonicacids, such as formic acid (3.55), oxaluric acid (2.27), cyanoaceticacid (2.47), phenylacetic acid (4.10), phenoxyacetic acid (2.99),fluoroacetic acid (2.59), chloroacetic acid (2.69), bromoacetic acid(2.72), iodoacetic acid (2.98), mercaptoacetic acid (3.43), vinylaceticacid (4.12), chloropropionic acid (2.71-3.92), 4-aminobutyric acid(4.03) and acrylic acid (4.26). High fatty carbonic acids may be alsoused, for example, malonic acid (2.65), succinic acid (4.00), glutaricacid (4.13), adipic acid (4.26), pimelic acid (4.31), azelatic acid(4.39), fumalic acid (2.85), grycolic acid (3.63), lactic acid (3.66),malic acid (3.24), tartaric acid (2.82-2.99), citric acid (2.87) and thelike. There are further glyoxylic acid (3.18), pyrvic acid (2.26),levulinic acid (4.44), anilinesulfonic acid (3.74-3.23), benzoic acid(4.20), aminobenzoic acid (2.02-3.12), chlorobenzoic acid (2.92-3.99),cyanobenzoic acid (3.60-3.55), nitrobenzoic acid ((2.17-3.45),hydroxybenzoic acid (4.08-4.58), anisic acid (4.09-4.48), fluorobenzoicacid (3.27-4.14), bromobenzoic acid (2.85-4.00), iodobenzoic acid(2.86-4.00), salicylic acid (2.81), naphtoic acid (3.70-4.16), cinnamicacid (3.88), mandelic acid (3.19), phthalic acid (2.75), isophthalicacid (3.50), telephthalic acid (3.54), nicotinic acid (2.05),2-furancarboxylic acid (2.97), 2,6-pyridinecarboxylic acid (2.09) andthe like.

[0094] As the mold releasing accelerator there are amino acids, such asasparatgine (2.14), aspartic acid (1.93), adenine (4.07), alanine(2.30), b-alanine (3.53), arginine (2.05), isoleucine (2.32), glycine(2.36), glutamine (2.17), glutamic acid (2.18), serine (2.13), tyrosine(2.17), tryptophane (2.35), threonine (2.21), norleucine (2.30), valine(2.26), phenylalanine (2.26), methionine (2.15), lysine (2.04) andleucine (2.35). There are also amino acid derivatives, such as adenosine(3.50), adenosine triphosphate (4.06), adenosine phosphate (3.65-3.80),L-alanyl-L-alanine (3.20), L-alanylglycine (3.10), b-alanylglycine(3.18), L-alanylglycyrglycine (3.24), b- alanylglycyrglycine (3.19),L-alanylglycyrglycyrglycine (3.18), glycyr-L-alanine (3.07),glycyr-b-alanine (3.91), glycyrglycyr-L-alanine (3.18),glycyrglycyrglycine (3.20), glycyrglycyrglycyrglycine (3.18),glycyrglycyr-L-histidine (2.72), glycyrglycyrglycyr-L-histidine (2.90),glycyr-DL-histidylglycine (3.26), glycyr-L-histidine (2.54),glycyr-L-leucine (3.09), g-L-glutamine-L-cicteinylglycine (2.03),N-methylglycine (sarcosine: 2.20), N,N-dimethylglycine (2.08),cytllurine (2.43), 3,4-dihydroxiphenylalanine (2.31), L-histidilglycine(2.84), L-phenylalanilglycine (3.02), L-propylglycine (3.07),L-leucil-L-tyrosine (3.15).

[0095] Preferable are formic acid, chloroacetic acid, haloacetic acid,halopropionic acid, acrylic acid, moronic acid, succinic acid, glutaricacid, fumalic acid, glycolic acid, lactic acid, malic acid, tartaricacid and citric acid.

[0096] These acids may be used as free acid, and their salts with alkalimetal, alkali earth metal and heavy metal. As alkali metal, there arelithium, potassium, and preferably sodium. As alkali earth metal, thereare barium, strontium, preferably calcium, magnesium. As heavy metalthere are zinc, tin, nickel and iron. Note that one or more than twosorts of the metals may be used.

[0097] In 1 g of cellulose ester, the acid and the salt thereof may be1×10⁻⁹-3×10⁻⁵ mol, preferably 1×10⁻⁸-2×10⁻⁵, particularly 1×10⁻⁷-1×10⁻⁵,and usually 5×10⁻⁷-5×10⁻⁶. The amount of the acids and salts in thecellulose esters may be determined with ionchromatography analysis.

Ionchromatography Analysis

[0098] 2.0 g of powders of dried cellulose acetate is measured. Hotwater 80 ml is added to the cellulose acetate to produce a mixture ofthe hot water and the cellulose acetate. The mixture is agitated andleft for a night in a tightly closed case. Thereafter, the mixture isagitated again and left for a while. Then the uppermost solution isobtained as a sample solution.

[0099] Note that the alkali metal and the alkali earth metal, if theiramount in the solution is not large, may be bound with acid group of thecellulose acetate. Total amount of alkali metal and alkali earth metalin cellulose acetate 1 g is determined not so as to have a bad influenceon heat resistance stabilization. Namely, the total amount is, in ionequivalent amount, less than 5.5×10⁻⁶, preferably 3.5×10⁻⁶, particularly2.5×10⁻⁶. Especially, the total amount is less than 1.5×10⁻⁶, moreespecially less than 0.3×10⁻⁶. In this case, when the film ishalf-dried, the film is easily peeled from the supporter without damage.The amount of the alkali metal and alkali earth metal is determined withatomic absorption analysis.

[0100] The mold releasing accelerators (1) and (2) are produced bymixing cellulose acetate with acids and salts of acid dissociationconstant pKa. Thereby the acids and the salts may be processed with thecellulose acetate during or after a process, such as a producing processof the cellulose acetate. The powdered or flaked cellulose acetate iscleansed or dipped in water or a solution. Further, the acids and thesalts may be added in the dope containing the cellulose acetate. Theprocessing the cellulose acetate with the acids and the salts arepreferably carried out in 10-70° C., preferably 15-50° C., for 1minute-12 hours. Thus the cellulose acetate can continuously have at least acarboxylic group even after the processing.

[0101] A method of producing a film from the cellulose ester isexplained now.

[0102] In FIG. 1, there are three dope preparing sections 15. each ofthe dope preparing section 15 has a mixing tank 1, a feed pump 2 and afilter 3. The mixing tank 1 is used for preparing the dope. In themixing tank 1, the cellulose triacetate and the additives are mixed. Themixing tank 1 is connected through the feed pump 2, the filter 3 and afeed block 32 to a die 4 of a doping section 16. The doping section 16is constructed of the die 4, a supporter a rotary drums 6, 7 and pluralguide rollers 8. Below the die 4, the rotary drums 6,7 and a belt 5 aredisposed. The belt 5 is used as the supporter, and is extendedly set therotary drums 6, 7 so as to confront to the die 4. From the die 4 thedope solution is provided on the belt 5. Further, above and below thebelt 5, a dried air blow supplier (not shown) is provided that is usedfor drying the dope solution on the belt 5. Thus the dope solution driedto become the film.

[0103] The rotary drum 6 is confronted to a peeling roller 9 of a dryingsection 17. The film is peeled from the supporter by the peeling roller9. The drying section has further guide rollers 10 and a drying room 12.In the drying section the film is perfectly dried and thereafter woundon a winding roller 11.

[0104] Before forming the film, the solvent evaporates. If P and Q aredetermined as weights of the dried film and the solvents respectively,the remain-evaporate ratio of the film is represented in R=(O/P)×100.The remain-evaporate ratio R is preferably more than 120%, andparticularly 200%. Further, the film may be dried after remove from thesupporter.

[0105] When the remain-evaporate ratio R is less than 120 wt. %, onlyone of the surfaces of the film is dried, and the film is hardly wound.Therefore, before winding, the film is dried again.

[0106] Further, it is preferably to carry out the nailing in the filmand cut down edges of the film before winding.

[0107] In FIG. 2A, a film 21 has an outer part 21 a which is made from asolution containing cotton linter and wood pulp in ratio (cottonlinter/wood pulp) 5/95-0/100. The solution contains as its solvent morethan 15 wt. % alcohol and hydrocarbons whose number of carbon is 1-10.In FIG. 2B, a film 21 further has an outer part 21 b which is made froma solution containing cotton linter and wood pulp in ratio (cottonlinter/wood pulp) 5/95-0/100. The solution contains as its solvent morethan 15 wt. % alcohol and hydrocarbons whose number of carbon is 1-10.

[0108] In FIG. 3A, a film 22 has a two-layers structure. A surface layer22 a of the film 22 is made from a solution containing cotton linter andwood pulp in ratio (cotton linter/wood pulp) 5/95-0/100. The solutioncontains as its solvent more than 15 wt. % of alcohol and hydrocarbonswhose number of carbon is 1-10. In FIG. 3B, a film 22 has a three layerstructure. A surface layer 22 b of the film 22 is made from a solutioncontaining cotton linter and wood pulp in ratio (cotton linter/woodpulp) 5/95-0/100. The solution contains as its solvent more than 15 wt.% alcohol and hydrocarbons whose number of carbon is 1-10.

[0109] Note that the present invention is not restricted in theembodiment illustrated in FIG. 2A, 2B, 3A and 3B, and may have fourlayer structure, for example.

[0110] In FIG. 4, the die 4 is provided with a nozzle 60, vessel 62 anda pump 63. The vessel 62 contains a mixture solvent (not shown) of goodand bad solvents of cellulose triacetate. The mixture solvent is fed outthrough the nozzle 60 by the pump 63.

[0111] In FIG. 5A, the die 4 is a feed block type. The supporter 33moves at a predetermined speed in an arrowed direction, and the die 4dopes the dope solution as a dope ribbon 31 on the belt 5. As shown inFIG. 5B, the feed block 32 is supplied with solutions 33 a, 33 b, 33 c,and has a structure to superpose them. Accordingly, the dope ribbon 31has a three-layers structure.

[0112] The solutions 33 a, 33 c are mixed with the mixture solvent fedout from the nozzle 60. Accordingly the dope ribbon 31 does not vibrateand edges of the dope ribbon become stable. As the bad solution thereare methanol, n-butanol and the like, and as the good solution there aremethylene chloride, methylacetate, and the like. Further, the solidcontent density of the solutions 33 a and 33 c becomes lower to preventthe skinning in the edges of the film.

[0113] As shown in FIG. 6A, the dope ribbon 31 is constructed of a firstlayer 31 a, a second layer 31 b and a third layer 31 c. The second layer31 b is sandwitched by the first and second layer 31 a, 31 c. As shownin FIG. 6B, in an edge of the dope ribbon 31 the first layer 31 a andthird layer 31 c becomes thicker. When D, S1 and S2 are determined asthickness of the dope ribbon 31, the first layer 31 a and the thirdlayers 31 c respectively, the following formula should be satisfied:

(S1+S2)D×100 >5 (%)

[0114] In FIG. 7, a die 40 may have three manifolds 41 a, 41 b, 41 c.The manifolds 41 a, 41 b, 41 c are provided with solutions 33 a, 33 b,33 c respectively, and in the die 40 the three layer dope 31 isconstructed.

[0115] Note that a solid content density of the solutions 33 a, 33 cconstructing outer sides of the three layer dope 31 is preferably by0.5% lower than that of the solution 33 b constructing a core layer ofthe three layer dope 31. Otherwise, the film may have slight projectionsor retractions on a surface thereof to cause damages in the edges of thefilm.

[0116] In the present invention, the alcohols and hydrocarbons having1-10 carbons are preferably contained more by 1 wt. %, particularly by 2wt. % in the solution 33 c than in the solutions 33 a, 33 b. Otherwise,it becomes hard to peel the film from the belt 5.

[0117] The temperature of a surface of the belt 5 is preferably between−20° C. and 25° C., particularly between −10° C. and 15° C. When thetemperature of the surface is below −20° C., a gas solidalization oftenoccurs to damage the surface of the film. When the temperature of thesurface is over 25° C., bubbles often generate and the film easilysticks on the belt 5 to cause the forming of slight projections andretractions.

[0118] In FIG. 8, three dies 50 a, 50 b, 50 c may be used. The threedies 50 a, 50 b, 50 c are supplied with the solutions 33 a, 33 b, 33 cto dope them on the supporter respectively. Thus the solution 33 a lieson the belt 5, the solution 33 a lies uppermost, and the solution 33 cis sandwitched between the solutions 33 a and 33 c.

[0119] In FIG. 9, the drying section 17 is further provided with atenter 84 between the peeling roller 9 and the drying chamber 12. By thetenter 84, the film is stretched and dried. As shown in FIG. 10, heaterplates are provided above and below the belt 5 to effectively dry thedope. Further, in FIG. 15 a drum 82 is used as the supporter.

[0120] In FIG. 12, the drying section has a drying chamber 13 too. Asshown in FIG. 13, the tenter 84 may be disposed between the dryingchambers 12, 13. In FIG. 14 the heater plates 83 are disposed above andbelow the belt 5, and in FIG. 15 a die 85 is provided so as to confrontto the drum 7. In FIG. 16 the drum 82 is used as the supporter, and inFIG. 17, a heater 85 is provided so as to confront to the drum 82.

[0121] A method of producing the film from the cellulose ester is notrestricted in them. For example the die 4 may be provided with apressure reduction chamber.

Preparation of Solutions Constructing Dope Solution

[0122] Preparation of solutions is explained as an example in whichcellulose triacetate is used as the polymer.

[0123] In the dope ribbon 31, the solid content density of the solution33 b for the intermittent layer 31 b in the dope ribbon 31 is preferably15-30 wt. %, especially 18-27 wt. %, and that of the solutions 33 a, 33c for the front and rear layers 31 a, 31 c is preferably 10-25 wt. %,especially 13-22 wt. %.

Swelling Process

[0124] Cellulose triacetate particles and solvents are mixed to producea mixed solution. Thereafter, the cellulose triacetate particles areswollen in the solvent. A temperature therefore is preferably between−10 and 55° C., and usually set in a room temperature. A ratio of thecellulose triacetate to the solvent is determined in accordance with alayer-structure in the cellulose triacetate film.

[0125] The solution 33 b for the intermittent layer 31 b preferablycontains cellulose triacetate between 13 and 27 wt. %, particularlybetween 16 and 25 wt. %, especially between 19 and 23 wt. %. Thesolutions 33 a, 33 c for the front and rear layers 31 a, 31 c preferablycontain cellulose triacetate between 9 and 23 wt. %, particularlybetween 12 and 21 wt. %, especially between 15 and 19 wt. %. Further,after mixing, it is preferable to enough agitate the cellulosetriacetate. Other materials may be added, for example, plasticizer,deterioration inhibitor, dynes and ultraviolet absorptive agent.

Heating Process

[0126] After swelling the cellulose triacetate particles, the mixedsolutions are preferably heated at a predetermined temperature over 130°C., particularly over 160° C., and especially over 180 ° C. However over250° C. , cellulose triacetate is discomposed, which causes to damagethe film to be produced. An averaged difference of increasedtemperatures per a minuet between start and end of heating is preferablymore than 1° C./min., particularly more than 2° C./min., especially 4°C./min., and more especially 8° C. /min, and upper limits thereof istheoretically 10000 ° C./min., technically 1000° C./min., andpractically 100° C./min. There are methods of heating, for example,autoclave, mutitube heat interchanger, screw pressure and static mixer.

[0127] A time length for heating the mixed solution is preferablybetween 20 seconds and 4 hours. When the time length is less than 20seconds, unsolved materials remain in the dope solution. When filtrationof the unsolved materials is carried out, a filtration life becomesshorter. The time length starts to be counted when the temperaturereaches the predetermined temperature, and ends to be counted when thetemperature become lower than the predetermined temperature.

Pressure-applying Process

[0128] Preferably, the mixture solution is heated thereby under applyingpressure so as to prevent the solvent from boiling, and the temperaturethereof is more than a boiling point under atmospheric pressure. Thus,the dope solution can have uniformity of quality. The pressure to beapplied is adjusted in relation of the temperature of the solution tothe boiling point of the solvent.

Cooling Process

[0129] When the cellulose triacetate hardly solves in the solvent andremains as unsolvable material in the solution, the solutions may becooled between −100 and −10° C. before or after being heated, so as toobtain the film having a good photographic character. When the mixturesolution is cooled down, the solvent penetrates in the cellulosetriacetate smoothly. Whether cellulose triacetate solves enough, it canbe perceived with eyes. When it does not solve enough, the heatingprocess and the cooling process are repeated. Note that in the coolingprocess, in order to prevent a mixture of water in the mixed solvent, avessel to be used is preferably tightly-closed. Further, when thepressure is made lower in the cooling process, the temperature becomeslower in shorter time. Accordingly, the vessel is preferablypressure-tight.

Relation of Sharing Viscosities

[0130] In order to prevent the generation of the skinning on an lip ofthe die, A/B and A′/B are preferably under 0.9 when A, A′ and B arerespectively determined as a sharing viscosity of the solution 33 a forthe front layer 31 a, that of the solution 33c for the rear layer 31cand that of the solution 33 b for the intermittent layer 33 b. Thesharing viscosities A, A′ are between 30 and 50 Pa·S and the sharingviscosity B is between 10 and 150 Pa·S , when a sharing velocity isbetween 1 and 3000 (1/sec) and the temperature for producing the film isbetween 30 and 40° C. Note that, when the intermittent layer isconstructed of plural layers, the sharing viscosity B is an average ofsharing viscosities of the plural layers.

Products

[0131] The film produced in the method described above is used as adeflector film. Further, the film is used as the optical compensationfilm when an optical compensation sheet is attached on the film.

Experiment 1 Preparation of Solution Composing Dope Solution

[0132] In Experiment 1 a solution S1 is used for the intermittent layerand made from following compounds in the above-described method forpreparing the dope solution. cellulose triacetate 100 part by weighttriphenylphosphate 7.8 part by weight biphenyldiphenylphosphate 3.9 partby weight (plasticiser) methylenchloride (first solvent) 300 part byweight methanol (second solvent) 65 part by weight ultravioletabsorptive agent 1.0 part by weight

[0133] Note that the cellulose triacetate used in Experiment 1 has 60.9%of acetification degree. The solid content density of the solution S1 is23.4 wt. %, and the additives are mixed in ratio of 13 wt. % to thecellulose triacetate.

[0134] In Experiment 1 a solution S2 is used for the surface layer, andmade from the following compounds. cellulose triacetate 87 part byweight triphenylphosphate 6.8 part by weight biphenyldiphenylphosphate3.4 part by weight (plasticiser) methylenchloride (first solvent) 300part by weight methanol (second solvent) 65 part by weight ultravioletabsorptive agent 0.9 part by weight

[0135] The solid content density of the solution S2 is 21.0 wt. %, andthe additives are mixed in ratio of 13 wt. % to the cellulosetriacetate.

[0136] In Experiment 1, a solution S3 is also used for the surfacelayer, and made from the following compounds. cellulose triacetate 77part by weight triphenylphosphate 6.0 part by weightbiphenyldiphenylphosphate 3.0 part by weight (plasticiser)methylenchloride (first solvent) 300 part by weight methanol (secondsolvent) 65 part by weight ultraviolet absorptive agent 0.9 part byweight

[0137] The solid content density of the solution S3 is 19.0 wt. %, andthe additives are mixed in ratio of 13 wt. % to the cellulosetriacetate.

Condition for Feeding Solvent

[0138] The solvent fed to the end of the slit of the die is a mixture ofmethanol (bad solvent to the cellulose triacetate) and methylenchloride(good solution to the cellulose triacetate) in ratio of 50:50. Thesolvent is fed in the feeding velocity of 0.2 ml/min.

Embodiment 1

[0139] In Embodiment 1 (E1 ), the solution S2 is used for the surfacelayers. In producing the film, the die 4 of the feed block type is used.The film is formed such that the averaged thickness of the film afterdrying the dope solution may be 60 μm, (S1+S2)D×100 may be 5%, and ratio(A/B) may be 0.72 when A and B are the shearing viscosity of thesolution for the surface layer and that of the solution for theintermittent layer respectively.

Embodiment 2

[0140] In Embodiment 2 (E2), the film is produced in the same conditionas in Embodiment 1, except that (S1+S2)D×100 is 30%.

Embodiment 3

[0141] In Embodiment 3 (E3), the solution S3 is used for the surfacelayer. In producing the film, the die 4 is used. The film is formed suchthat the averaged thickness of the film after drying the solutions maybe 60 μm, (S1+S2)D×100 may be 30%, and the ratio (A/B) may be 0.52.

Embodiment 4

[0142] In Embodiment 4 (E4), mixture solvent is fed to the end of thedie in preparation of the film. Other condition is as same as inEmbodiment 4.

Comparision 1

[0143] In Comparision 1 (C1), the film is formed only of the solutionS1. In this case, (S1+S2)D×100 is 0, and the ratio A/B is 1. Otherconditions are as same as in Embodiment 1.

Comparision 2

[0144] In Comparision 2 (C2), the mixture solvent is fed to the end ofthe die in preparation of the film. Other condition is as same as inEmbodiment 1.

Evaluation 1

[0145] Evaluation of the film is made to generation frequency ofskinning as follows: The skinning generates in few days N The skinninggenerates after more than a month U The skinning generates after morethan three months G The skinning generates after more than six months B

[0146] respectively.

Evaluation 2

[0147] Evaluation of surface situation of film is made as follows: Worsethan the limitation of usable quality N As same as the limitation ofusable quality U More than the limitation of usable quality G

[0148] TABLE 1 E1 E2 E3 E4 C1 C2 Solution for surface S2 S2 S3 S3 — —layer (S1 + S2)/D (%) 5 30 30 30 0 0 A/B 0.72 0.72 0.52 0.52 1 1 Feedingsolvent No No No Yes No Yes Evaluation 1 G G G B N B Evaluation 2 U G GG N U

[0149] The results shown in Table 1 teaches that the film becomes betterwhen it is formed of the solution S3 having a lower solid contentdensity than the solution S2. Accordingly, the dope solution used forproducing the film preferably has the lower solid content density.Further, when the mixture solvent is fed to the end of the die, thequality of the film becomes higher.

Experiment 2

[0150] In Experiment 2, methylacetate is used as the main solvents ofthe dope solution. Evaluations of the embodiments 5-8 and Comparisions3,4 are as same as those of Embodiment 1-5 and Comparisions 1,2.

Preparation of Solution Composing Dope Solution

[0151] In Experiment 2, a solution S4 is used for the intermittentlayer, and made from following compounds in the above-described methodfor preparing the solution S4. cellulose triacetate 100 part by weighttriphenylphosphate 7.8 part by weight biphenyldiphenylphosphate 3.9 partby weight (plasticiser) methyl acetate (first solvent) 260 part byweight mixture solvent (second solvent) 110 part by weight ultravioletabsorptive agent 0.9 part by weight

[0152] The mixture solvent of the second solvent contains acetone,ethanol, methanol, n-butanol in ratio 2:1:1:1. The solid content densityof the solution S4 is 23.4 wt. %, and the additives are mixed in ratioof 13 wt. % to the cellulose triacetate.

[0153] In Experiment 2, a solution S5 is used for the surface layer, andmade from the following compounds. cellulose triacetate 87 part byweight triphenylphosphate 6.8 part by weight biphenyldiphenylphosphate3.4 part by weight (plasticiser) methylenchloride (first solvent) 265.5part by weight methanol (second solvent) 113.6 part by weightultraviolet absorptive agent 0.9 part by weight

[0154] The solid content density of the solution S5 is 20.6 wt. %, andthe additives are mixed in ratio of 13 wt. % to the cellulosetriacetate.

[0155] In Experiment 2, a solution S6 is used for the surface layer ismade from the following compounds. cellulose triacetate 77 part byweight triphenylphosphate 6.0 part by weight biphenyldiphenylphosphate3.0 part by weight (plasticiser) methyl acetate (first solvent) 266.5Part by weight mixture solvent (second solvent) 114.3 part by weightultraviolet absorptive agent 0.9 part by weight

[0156] The solid content density of the solution S6 is 18.6 wt. %, andthe additives are mixed in ratio of 13 wt. % to the cellulosetriacetate.

Embodiment 5

[0157] In Embodiment 5 (E5), the solution S4 is used for the surfacelayers. In producing the film, a die of the feed block type is used. Thefilm is formed such that the averaged thickness of the film after dryingthe dope solutions may be 60 μm, (S1+S2)D×100 may be 5%, and the ratioA/B may be 0.68.

Embodiment 6

[0158] In Embodiment 6 (E6), the film is produced in the same conditionas in Embodiment 5, except that (S1+S2)D×100 is 25%.

Embodiment 7

[0159] In Embodiment 7 (E7), the solution S6 is used for the surfacelayer. In producing the film, a die of the feed block type is used. Thefilm is formed such that the averaged thickness of the film after dryingthe solution S6 may be 60 mm, (S1+S2)D×100 may be 25%, and the ratio A/Bmay be 0.47.

Embodiment 8

[0160] In Embodiment 8 (E8), mixture solvent is fed to the end of thedie in preparation of the film. Other condition is as same as inEmbodiment 7.

Comparision 3

[0161] In Comparision 3 (C3), the film is formed only of the solutionS4. In this case, (S1+S2)D×100 is 0%, and the ratio A/B is 1. Otherconditions are as same as in embodiment 5.

Comparision 4

[0162] In Comparision 4 (C4), the mixture solvent is fed to the end ofthe die in preparation of the film. Other condition is as same as inEmbodiment 3. TABLE 2 E5 E6 E7 E8 C3 C4 Solution for surface S5 S5 S6 S6— — layer (S1 + S2)/D (%) 5 25 25 25 0 0 A/B 0.68 0.68 0.47 0.47 1 1Feeding solvent No No No Yes No Yes Evaluation 1 G G G B N B Evaluation2 U G G G N G

[0163] The results shown in Table 2 is almost as same as that in theTable 1. The methylenechloride halmfully influences on circumstance.Accordingly, the present invention is carried out by using methylacetatewhich has no influence on circumstance so much.

Experiment 3

[0164] In Experiment 3 chloride solvents are used in the dope solution.To the dope solution, a 40° C. warm air is blown to form the film whosetotal thickness is 80 μm, and after peeled from the supporter, the filmis dried in 120° C. for 10 minutes.

Embodiment 9

[0165] In Embodiment 9 (E9), the film is produced so as to have only onelayer.

Embodiment 10

[0166] In Embodiment 10 (E10), the film is produced by using the die 4illustrated in FIG. 4 so as to have three layers.

Embodiment 11

[0167] In Embodiment 11 (E11), the film is produced by using the die 4illustrated in FIG. 4 so as to have two layers.

Embodiment 12

[0168] In Embodiment 12 (E12), the film is produced so as to have onlyone layer.

Embodiment 13

[0169] In Embodiment 13 (E13), the film is produced by using the die 4illustrated in FIG. 4 so as to have three layers.

Embodiment 14

[0170] In Embodiment 14 (E14), the film is produced by using the die 4illustrated in FIG. 4 so as to have three layers.

Comparision 5

[0171] In Comparision 5 (C5), the film is produced so as to have onlyone layer.

[0172] In Experiments 9-14 and Comparision 5, following solutions 7-11are used. The composition of the each solution in the dope solution isas follows. <Solution 7 (S7)> cellulose triacetate 23 parts by weightRatio of masses (cotton linter/wood pulp = 60/40) triphenylphosphate 3parts by weight mixture solvent 74 part by weight Ratio of masses(dichloromethane/methanol = 77/23) <Solution 8 (S8)> cellulosetriacetate 23 parts by weight Ratio of masses (cotton linter/wood pulp =0/100) triphenylphosphate 3 parts by weight mixture solvent 74 part byweight Ratio of masses (dichloromethane/methanol = 77/23) <Solution 9(S9)> cellulose triacetate 20 parts by weight Ratio of masses (cottonlinter/wood pulp = 0/100) triphenylphosphate 3 parts by weight mixturesolvent 77 part by weight Ratio of masses (dichloromethane/methanol =77/23) <Solution 10 (S10)> cellulose triacetate 23 parts by weight Ratioof masses (cotton linter/wood pulp = 0/100) triphenylphosphate 3 partsby weight mixture solvent 74 part by weight Ratio of masses(dichloromethane/methanol = 76/24) <Solution 11 (S11)> cellulosetriacetate 23 parts by weight Ratio of masses (cotton linter/wood pulp =0/100) triphenylphosphate 3 parts by weight mixture solvent 74 part byweight Ratio of masses (dichloromethane/methanol = 77/23) Citric acid(mold releasing accelerator) 300 PPM in weight of the solution S11.

Method of Forming Deflector

[0173] Polyvinyl alcohol film (75 μm) is set in iodine/potassium iodidesolution and boric acid solution sequentially, and thereafter extendedin a lengthwise direction of the film. Then the film is dried to formthe polarizer.

[0174] Further, the film is set in alkali solution, acid solution andwater sequentially. Thereafter the film is dried, and the process of thesurface of the film is carried out. Then the film is adhered to thepolarizer and dried again.

Forming Estimation Panel for Estimation Frame

[0175] An adhesive agent is applied to a surface of the deflector cut insize of 15 inches. Then the deflector is adhered to the both surfaces ofa soda glass to form an estimation panel such that orientation axes ofthe deflector and the soda glass are perpendicular to each other.

Estimation of Frame

[0176] The estimation panel is processed in 40° C. and 95% atmospherefor 17 hours, and thereafter set in the room temperature for 24 hours.Thereafter, the estimation panel is disposed on a schaukasten, andoptical creases are estimated with eyes as follows

[0177] AA: there are no optical creases (best)

[0178] A: there are few obvious optical creases in edges of the frame(good)

[0179] B: there are distinct creases in the edges of the frame (usable)

[0180] C: there are creases also in a central part of the frame(unusable)

[0181] The result of Experiment 1 is shown in Table 3. In Table 3, L1,L2, L3 are respectively the uppermost, intermittent and lowest layers ofthe dope solution on the supporter. Further, H1, H2, H3 are respectivelythickness of layers formed from the uppermost, intermittent, and lowestlayers of the dope solution after dried. EV is ratio of the evaporatedsolvents to the film just after peeled from the supporter. TABLE 3Thickness Estimation Composition of dope ratio EV 13 20 L1 L2 L3 H1 H2H3 Wt % inch inch E9 S8 S8 S8 — — — 100 A B E10 S8 S7 S8 5 70 5 100 A BE11 S8 S8 S11 — 75 5 200 AA AA E12 S8 S8 S8 — — — 140 AA A E13 S9 S8 S95 70 5 100 AA A E14 S8 S8 S10 5 70 5 160 AA A C5 S7 S7 S7 — — — 100 B C

Experiment 4

[0182] In Experiment 4 non-chloride solvents are used in the dopesolution. To the dope solution, a 60° C. warm air is blown to form thefilm whose total thickness is 80 μm, and after peeled from thesupporter, the film is dried in 120° C. for 10 minutes.

Embodiment 15

[0183] In Embodiment 15 (E15), the film is produced so as to have only asingle layer.

Embodiment 16

[0184] In Embodiment 16 (E16), the film is produced by using the die 40so as to have three layers.

Embodiment 17

[0185] In Embodiment 17 (E17), the film is produced by using the die 40so as to have two layers.

Embodiment 18

[0186] In Embodiment 18 (E18), the film is produced so as to have only asingle layer.

Embodiment 19

[0187] In Embodiment 19 (E19), the film is produced by using the die 40illustrated in FIG. 7 so as to have three layers.

Embodiment 20

[0188] In Embodiment 20 (E20), the film is produced by using the dies 50a , 50 b, 50 c illustrated in FIG. 8 so as to have three layers.

Comparision 6

[0189] In Comparision 5 (C5), the film is produced so as to have only asingle layer.

[0190] In Experiments 15-20 and Comparision 6, following solutions 12-16are used. The composition of each solution in the solution is asfollows. <Solution 12 (S12)> cellulose triacetate 22 parts by weightRatio of masses (cotton linter/wood pulp = 60/40) triphenylphosphate 3parts by weight mixture solvent 74 part by weight Ratio of masses(methyl acetate/acetone/alcohol = 45/20/15) +TL,1/10 <Solution 13 (S13)>cellulose triacetate 22 parts by weight Ratio of masses (cottonlinter/wood pulp = 0/100) triphenylphosphate 3 parts by weight mixturesolvent 74 part by weight Ratio of masses (methylacetate/acetone/alcohol = 45/20/15) <Solution 14 (S14)> cellulosetriacetate 20 parts by weight Ratio of masses (cotton linter/wood pulp =0/100) triphenylphosphate 3 parts by weight mixture solvent 77 part byweight Ratio of masses (methyl acetate/acetone/alcohol = 45/20/15)<Solution 15 (S15)> cellulose triacetate 22 parts by weight Ratio ofmasses (cotton linter/wood pulp = 0/100) triphenylphosphate 3 parts byweight mixture solvent 74 part by weight Ratio of masses (methylacetate/acetone/alcohol = 44/20/16) <Solution 16 (S16)> cellulosetriacetate 23 parts by weight Ratio of masses (cotton linter/wood pulp =0/100) triphenylphosphate 3 parts by weight mixture solvent 74 part byweight Ratio of masses (methyl acetate/acetone/alcohol = 45/20/15)Citric acid (mold releasing accelerator) 300 PPM in weight of thesolution S11.

[0191] In Experiment 4, the estimation panel is made and the estimationof is carried out as same as in Experiment 3. TABLE 4 Composition ofdope Thickness Estimation solution ratio EV 13 20 L1 L2 L3 H1 H2 H3 wt %inch inch E15 S13 S13 S13 — — — 100 A B E16 S13 S12 S13 5 70 5 100 A BE17 S13 S13 S11 — 75 5 200 AA AA E18 S13 S13 S13 — — — 140 AA A E19 S14S13 S14 5 70 5 100 AA A E20 S13 S13 S15 5 70 5 160 AA A C6 S12 S12 S12 —— — 100 B C

[0192] Various changes and modifications are possible in the presentinvention and may be understood to be within the present invention.

What is claimed is:
 1. A method of producing a cellulose ester filmhaving a front layer, an intermittent layer and a rear layer by using adope solution, said front, intermittent, and rear layers beingrespectively formed of first, second and third solutions which constructsaid dope solution, said method comprising a step of: doping said dopesolution from a die having a slit on a supporter, in said dope solutiona solid content density of each of said first and third solutions beinglower than that of said second solution, and satisfying a condition thatA/B is under 0.9, wherein A and B are a sharing viscosity of said firstsolution or said third solution and a sharing viscosity of said secondsolution respectively.
 2. A method according to claim 1, wherein whensaid dope solution is doped as a dope ribbon from said die, a totalthickness of edges of said front layer and said rear layer is more than5% of a total thickness of said dope ribbon.
 3. A method according toclaim 1, wherein said intermittent layer is constituted of plurallayers.
 4. A method according to claim 1, wherein said first solution,said second solution and said third solution are doped in a superposedsituation on said supporter, or sequentially doped on said supporter. 5.A method according to claim 3, wherein said die is provided with a feedblock for superposing said first, second and third solutions in asmaller width than said dope solution so as to said first, second, thirdsolutions as said dope solution into said die.
 6. A method according toclaim 4, wherein said die is provided with a feed block for superposingsaid first, second and third solutions in a smaller width than said dopesolution so as to said first, second, third solutions as said dopesolution into said die.
 7. A method according to claim 3, wherein saiddie includes three manifolds for containing said first, second and thirdsolutions respectively.
 8. A method according to claim 4, wherein saiddie includes three manifolds for containing said first, second and thirdsolutions respectively.
 9. A method according to claim 1, furthercomprising a step of: feeding a mixture solvent from both sides of aslit of said die, said mixture solvent contains a bad solution of 30-90wt. % to solutes in said dope solution.
 10. A method according to claim1, wherein a thickness of said cellulose ester film formed by dryingsaid dope solution is 20-200 μm.
 11. A method according to claim 10,wherein said cellulose ester film is used as deflector film.
 12. Amethod according to claim 10, wherein said cellulose ester film is usesas an optical compensation film.
 13. A method of producing a celluloseester film constructed of plural layers by using a die having pluralmanifold, comprising steps of doping on a supporter a dope solutioncomposed of solutions contained in said respective manifold, a solventof said dope solution being alcohol having 1-10 carbons and includingmore than 15 wt. % of hydrocarbon; drying said dope solution on saidsupporter to form said cellulose ester film; peeling said celluloseester film from said supporter; and drying said cellulose ester filmafter peeling from said supporter such that in at least one of surfacelayers of said plural layers a ratio of cotton linter and wood pulp(cotton linter/wood pulp) may be 5/95-0/100.
 14. A method according toclaim 13, wherein other layers than said surface layers of saidcellulose ester film are formed from one or more of said pluralsolutions of cotton linter and wood pulp in ratio of mass (cottonlinter/wood pulp) between 5/95 and 0/100.
 15. A method according toclaim 13, wherein a peeling accelerator is added to said dope solution.16. A method according to claim 15, wherein said dope solution iscomposed of plural solutions, one of said plural solutions contains saidpeeling accelerator and is doped so as to lie on said supporter.
 17. Amethod according to claim 13, wherein after peeling from said supporterand drying, when P, Q and R are solid mass of said cellulose ester film,evaporated mass from said dope solution and a ratio of evaporatedsolvents to said cellulose ester film respectively, R is determined as(Q/P)×100 (wt. %) and more than 120 wt. %.
 18. A method according toclaim 14, wherein said solutions are a first solution, a second solutionand a third solution, said first and third solutions are used for eachof said surface layers, solid content density of said first and thirdsolutions are 0.5% lower than that of said second solution.
 19. A methodaccording to claim 18, wherein said third solution is doped so as tocontact to said supporter, and content of alcohol of 1-10 carbon numbersand carbon hydride in a solvent of said third solution is more than 1%larger than said first and second solutions.
 20. A method according toclaim 13, wherein a surface temperature of said supporter is between −20and 25° C.
 21. A method according to claim 13, wherein said celluloseester film is used as a deflector protecting film.
 22. A method ofproducing a cellulose ester film by using a die provided with a feedblock in which plural solutions are superposed so as to have a smallerwidth than on a lip of said die, said method comprising steps of: dopingon a supporter a dope solution composed of solutions superposed in saidfeed block, a solvent of said dope solution being alcohol having 1-10carbons and including more than 15 wt. % of hydrocarbon; drying saiddope solution on said supporter to form said cellulose ester filmconstructed of a same number of layers as said plural solutions; peelingsaid cellulose ester film from said supporter; and drying said celluloseester film after peeling from said supporter, such that in at least oneof surface layers of said cellulose ester film a ratio of cotton linterand wood pulp (cotton linter / wood pulp) may be between 5/95 and 0/100.23. A method according to claim 22, wherein other layers than saidsurface layers of said cellulose ester film are formed from one or moreof said plural solutions of cotton linter and wood pulp in ratio of mass(cotton linter/wood pulp) 5/95-0/100.
 24. A method according to claim22, wherein a peeling accelerator is added to said dope solution.
 25. Amethod according to claim 24, wherein said dope solution is composed ofplural solutions, one of said plural solutions contains said peelingaccelerator and is doped so as to confront to said supporter.
 26. Amethod according to claim 22, wherein after peeling from said supporterand drying, when P, Q and R are solid mass of said cellulose ester film,evaporated mass from said dope solution and a ratio of evaporatedsolvents to said cellulose ester film respectively, R is determined as(Q/P)×100 (wt. %) and more than 120 wt. %. 27.A method according toclaim 23, wherein said solutions are a first solution, a second solutionand a third solution, said first and third solutions are used for eachof said surface layers, solid content density of said first and thirdsolutions are 0.5% lower than that of said second solution. 28.A methodaccording to claim 27, wherein said third solution is doped so as tocontact to said supporter, and content of alcohol of 1-10 carbon numbersand carbon hydride in a solvent of said third solution is more than 1%larger than said first and second solutions. 29.A method according toclaim 22, wherein a surface temperature of said supporter is between −10and 25° C. 30.A method according to claim 22, wherein said celluloseester film is used as a deflector protecting film. 31.A method ofproducing a cellulose ester film by using plural dies, comprising stepsof: doping on a supporter a same number of dope solutions as said pluraldies, a solvent of said dope solutions being alcohol having 1-10 carbonsand including more than 15 wt. % of hydrocarbon; drying said dopesolution on said supporter to form said cellulose ester film composed ofa same number of layers as said plural die; peeling said cellulose esterfilm from said supporter; and drying said cellulose ester film afterpeeling from said supporter, such that in at least one of surface layersof said cellulose ester film a ratio of cotton linter and wood pulp(cotton linter/wood pulp) may be between 5/95 and 0/100.
 32. A method ofproducing a cellulose ester film by using a die, comprising steps of:doping a dope solution on a supporter, a solvent of said dope solutionbeing alcohol having 1-10 carbons and including more than 15 wt. % ofhydrocarbon; drying said dope solution on said supporter to form saidcellulose ester film, peeling said cellulose ester film from saidsupporter; and drying said cellulose ester film after peeling from saidsupporter, such that in at least a part of 0.5 μm from a surface of saidcellulose ester film a ratio of cotton linter and wood pulp (cottonlinter/wood pulp) may be between 5/95 and 0/100.